My prior U.S. Pat. No. 4,559,905, Dec. 24, 1985, and Kapplinger U.S. Pat. No. 4,100,885, July 18. 1978, disclose representative waterers of the prior art. The waterers of each of these patents are best suited for large animals. There is a risk that small animals such as small pigs may actually enter the access opening and drown in the water supply in the tank. Another problem for small animals is that the access openings are in horizontal planes substantially elevated above the ground requiring the animal to gain access from above which requires the small animal to climb up the side of the waterer to reach the opening. If the access opening is not horizontally oriented the buoyant spherical float will not close the access opening.
Another problem with lid-type access closures, such as in the Kapplinger patent, is that water dripping from the animal's mouth onto the surface around the access opening will freeze causing ice build up which will then prevent the lid from closing tightly down around the access opening which will in turn allow the cold outside air to enter the tank and freeze the reservoir of water. It is very important that the access opening be tightly sealed when an animal is not drinking.